Cement roofing panels are usually made from a mixture of cement and sand in the ratio by weight of 1:3 by adding water to the mixture to prepare a flowable mortar, press-molding the mortar on a die board and curing the resulting moldings. However roofing panels obtained have the drawbacks of being heavy, having insufficient heat-insulating properties and being prone to cracking during curing.
The present applicant (or assignee) has previously invented lightweight roofing panels made from a mixture of cement and an inorganic foamed aggregate such as pumice, foamed siliceous sand or the like by adding a small amount of water, i.e. about 3 to 15% by weight of water based on the mixture, to wet the starting mixture, placing the mixture into molds, and pressing the mixture at a pressure of 200 to 600 kg/cm.sup.2 and curing the molded pieces. Since the inorganic foamed aggregate remains porous as incorporated in the cement roofing panels obtained by the dry method, the panels have the advantages of having a reduced specific gravity, being lightweight, possessing improved heat-insulating properties and being less susceptible to cracking during curing.
This invention relates to an apparatus for molding roofing panels by the dry method described above, and more particularly to an apparatus for producing roofing panels, as shown in FIGS. 9 and 10, which include a main body 2 and an insert portion 4 extending stepwise from one end of the main body 2, the main body 2 and the insert portion 4 having substantially the same thickness.
Such roofing panels having a stepped portion are adapted for use on the ridge of roofs as arranged continuously in a row as illustrated in FIG. 10, with the insert portion 4 of each panel fitted to the other end of the adjacent panel. Roofing panels of this type are not limited to the illustrated arched panels but include those L- or V-shaped in cross section, those in the form of a flat plate, etc. The molding apparatus of this invention is useful for the production of various kinds of roofing panels having a stepped portion.